Flush valve control stop



FIG. 1 is a perspective view of my new design for a flush valve control stop;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror image thereof;

FIG. 4 is a left side elevational view thereof; and,

FIG. 5 is a bottom plan view. 

The ornamental design for a flush valve control stop, as shown and described. 